Low differential switching apparatus



Jan. 13, 1953 R. T. sQulER 2,625,046

LOW DIFFERENTIAL SWITCHING APPARATUS Filed bee. 18, 1950 2 Sl-lEETS-SHEET 1 (Iitorneg Jan. 13, 1953 R. T. SQUIER 2,625,046

LOW DIFFERENTIAL SWITCHING APPARATUS Filed Dec. 18, 1950 2 Si-lEETS-Sl-IEET 2 INVENTOR. /1 RALPH T. SQUIER ATTORNEY Patented Jan. 13, 1953 LOW DIFFERENTIAL SWITCHING APPARATUS Ralph T. Squier, Minneapolis, Minn., assignor to Minneapolis-Honeywell Regulator Company, Minneapolis, Minn, a corporation of Delaware Application December 18, 1950, Serial No; 201,385

19 Claims.

This invention relates to the field of electrical instrumentation and control, and embodies improvements in fluid switch mountings, fluid switch control systems, and systems for regulating the precession of gyroscopes.

This application is a continuation in part in my copending application Serial No. 777,179 filed October 1, 1947 on Low Differential Switching Apparatus.

vFluid switches themselves are well known, and the. use of such switches to control the operation of torque motors for processing gyroscopic instruments to maintain a desired attitude is also known. However, gyroscopic precession systems in which the control of the fluid switch rests solely in the position of the gyroscope are subject to certain disabilities such as lack of uniformity of operation, tendency to hunt, insufficient sensitivity, non-interchangeability of fluid switch units, etc., which disabilities it is the purpose of this invention to overcome or minimize.

An object of the invention is to provide an improved system for controlling the precession of gyroscopes. Other objects are to improve the sensitivity of fluid switches by decreasing the differential angle, to provide fluid switch mountings whereby control functions of the switch may in effect be partially anticipated, and to provide electromagnetically actuated means for causing limited movement between a fluid switch and the movable body supporting it.

A further object of this invention is toprovide a system for processing a gyroscope in which a liquid contact type circuit controller is continuously oscillated and subjected to tilt of the gyroscope 'from a normal position to control prec'ession of the gyroscope in proportion to the amount of tilt thereof.

Various other objects, advantages, and features of novelty which characterize the invention are pointed out with particularity in the claims annexed hereto and forming a part hereof. However, for a better understanding of the invention, its advantages, and objects attained by its use, reference should be had to the subjoined drawing, which forms a further part hereof, and to the accompanying descriptive matter, in which there are illustrated and described certain preferred embodiments of the invention. In the drawing:

Figure l is a generalized View of a gyroscope erecting system according to my invention, the gyroscope beingshown in plan;

Figure 2 is a view in elevation showing details of a fluid switch suitable for use in the system. of Figure l;

Figure 3 is a view similar to Figure 1, showing a modification of the system;

Figures 4 and 5 are elevational views showing details of one fluid switch suitable for use in the system of Figure 3; and

Figure 6 is a view in elevation showing details of another fluid switch suitable for use in the system of Figure 3.

Figure 1 shows a housing [0 in which a gyroscopic rotor, not shown, is arranged for rotation in a direction indicated by the arrow I I about a vertical axis 1. The rotor contained in housing I0 is maintained in rotation at high speed, and there is indicated at 23 suitable electric motor structure for performing this function.

Housing I0 is mounted for pivotal movement, with respect to a Cardan ring l2, about a first normally horizontal axis 8, and Cardan ring [2 in turn is mounted for pivotal movement, with respect toa pair of support members l3 and H, about a second normal horizontal axis 9, at right angles to the first.

A reversible torque motor i5 is provided for applying torque between housing lll and Cardan ring I2, and a second torque motor 16 is provided for causing torque between Cardan ring l2 and support member 14. Torque motor [5 is shown to comprise a first component I'l, efi'ective when energized to cause application of torque in a first direction, and a second component 20, effective when energized to cause application of torque in the opposite direction. Similarly, torque motor l B is shown to comprise a first component 2|, ffectivetoapply torque in a first direction, and a second component 22 effective t apply torque in the opposite direction.

The structure thus far disclosed is conventional and the showing is therefore schematic.

Mounted on housing I0 there is shown in Fig ure 1 a mercury switch 24, of which the constructional details are shown in Figure 2. The switch comprises a glass envelope 25 containing a globule of mercury 26. A pair of electrodes 21 and 30 pass through the envelope, and the dimensions of the -envelope,'the amount of mercury, and the position and length of the electrodes are so chosen that when the switch is tilted clockwise silient base member 34, one end of which is fastened by machine screws 35 to housing It], and the other end of which is adjustably spaced from housing ill by a machine screw 36 threadedly engaging the resilient member, to which it is locked in any desired adjusted position by a lock nut 37. Support-3 I .includes a plate member) shaped to perform. a number of. supporting. functions. At one end, plate member 451 is shaped to anchor the ends of a set of crossed reeds M, 42 which act as a bearing for armature 32. At the other end plate member 48 is reverselybent'so as'to cooperate With armature 32 to act as a stop-for movement thereof. In order. that this stopping function may be adjustable; amachine screw 43 threadedly engages this eIidpf'member- 4G,:andris locked in any desired positionby a. lock nut 45. Plate member as is fastened to'member' 34 by machine screws 45, and is arranged intermediate its ends to support electromagnetic member 33, which. is attachedto it by screws 46.

Electromagnetic member 33. is .shown. to compriseta U-shaped-core M .of ferromagnetic material :on one "leg. of which there. is pressedor otherwise suitably mounted afcrm ,or spoolj52. car- :rying a=-winding 5!.

Armature .32: is. shown to comprise afframe member 53 of non-magnetic material formed in- -wtermediate-its end toreceive the ends of reeds 4i end-42 not fastened to support 3!. Near one 1 end,: framemember. 53 .is provided with a;strip fi itof: ferromagnetic .material suitably mounted (for cooperation-with electromagnetic .member J33 ,to .cause movementrof. .armature 32. away from stop 33 when windingt l, isenergized;fIhismotion .soflthearmature. is \opposed by. a spring 55.:con-

nectedQbetween plate. member 49 and. armature 32,-and. adjustably. tensioned by ascrewit whose ring 5| is. unenergized, spring .55maintains arma- .sture, 32 ..-in. contact with stop 23.

The glass envelope is mountedon armature32 ..-by-.a pair of. bracket members; 69 v and e l fastened to frame member 53 by screws 62 and"$3."When .iwindingq5i :is .energized,..armature. 32 pivots upon its reed bearings in a counter-clockwisedirection -.unt-il it engagescorei'handthis tilts envelope 25 50:.thflt-th8 mercurymovestothte left in the en- -velope;to. assume,.a-position.in which the elec- -.trical .connection between electrodesd'l .and '3G ...:is.broken.. When winding 5! is vdeenergized, spring .55 .causes .thearmature to .pivot' in a clockwise "direction until it engagesstopmeansddahd this tilts envelopelfi so that themercurymoves to the ..-right to assume a. position .in which. the; electrical connection between electrodes..Z'l.1and 3fi. is comz..pleted.

Limitedmovement of envelope 25..relative to the .--housing.lii on whichthe switch..is..mounted.is thus-permitted. by pivotal movementpf .armature.32..on its crossedreeds HA2: this movement z-is:limited-atone. extremity by contact of. strip 54. with core 47, and .at .the other extremity ,by ..contact;of armature 32 withscrew 43.. This moveimentis of. course, inaddition to any tilting movemment of. housing ilwhich may. takeplace.

As. shown inFigure 2, one terminalof winding J5!-. is-.connected.with electrode 2! ,by. an. electrical. conductor. 54,. and another electrical con- ..ductor 1.651s. also connected thereto. A further electrical conductor-.66. isconnected. to the other .terminalof. solenoid winding 5i. and yet another 1...electricalconductor 8?. .is. connected .to the other ..electrode..3l3.' I1These conductors have been identified. by}..the .same. referencenumerals in 'Figure 10 -sistor 83, conductor 84, winding 2| of torque motor [6, and conductor 65, to electrode 21. Electrode-3d is grounded, thus completing a circuit from the source through torque motor it whenever the envelope. is tilted in a clockwise direcrtiOIl asseenin Figure 2.

...-1.A;circuit..may be also traced from the ungrounded terminal ll of the source through conductorsfdand Hyswitch 8U, conductors 8|, 85 and'BS, variable resistor 8'1, conductor 99, winding :0 22 of torque motor l6, ground connections SI and .l i,.-switch 13,.and-conductor l2 backtoterminal 3% oflthesource. It willbe seen byinspe'ctionof I the circuits .just trac'ed'j that winding 22 of torque .motor l.6..is continuously energizedfrom thesource, while winding 2i. of the torque motor is energized ...only when the mercury makes connection between i elect-rodeszlandtll. The force exerted by'com- .ponent 2 Lwhen energized is designedto be twice as great as that exerted by component22, so that whenbothcomponents are energized, the effec- ...tive..torque.output of the motor is equal in "mag- .nitude and opposite in "directiorrto that" when .cnly .one component 22 is energized.

"'ZWhenever the mercury'cornpletes' the electrical 3.3...conne'ction between electrodes 21 and 30,.aifur- Llther. circuitmay be traced from. terminal I I fof'the .rsource through conductors 15,16, and65,iwinding 25L conductor $4,.electrode 27, mercuryflZSfelectrode 3d, eroundconnections. 6'1 ancl'id; switchl3 so and conductor.12 to. terminal.ltfof'thesource. The purpose of this further circuit will nowbe explained.

It. is a well known characteristic" "of fluid switches such as switch :24 that adefiniteand (is sometimes considerable angle of tilt "must-"be ,passed through between the position of the-envelope in which. the mercurycompletes the con- .nectionbetween. electrodes '211and30 and thatin which the mercury breaks that connectionfThis angle will .be referred to as the differential: angle of the switch, and depends on the size; and" shape -of the envelope, the amount ;of mercury, the length and position'of the electrodes; and other factors. .Forideal performance of' control functions with precise. controlling devicesthe diiferential ..angle of the switch would 'of'course"be v..mini,mum, This is never achieved .in practice, and even a close approachtoanegligibly small ....difierentia1 anglegreatly increases the. cost "of .,man'ufacturing. these tubes on a production basis,

both .by..increasing the manufacturing Skillsre- .quired-.to..produce such. units, and by narrowing .the. tclerancestoa point where too many of the .units manufactured .must be rejected. Mercury 65. switch 24, as. disclosed in the present application, however, is. designed to obtain the eifectof a very .small differentialangle from a fluid switch whose actual. differential. vmay be .many times that desired. 7o When mercury switch 24 is in the condition shown'in'Figure 2, only. component 22 of;torque motor 26 is energized, and this component isact- ..ing .to cause rotation. of housing It in Cardan .ring. l2 in.such a direction as to raise'the left end portion of the housing as shown'in Figure? and to lower the right handv portion. Th position of support member 3I is so adjusted by operating screw 36 that just as housing In passes clockwise through a level condition mercury globule 26 moves to the right, causing energization of component 2| of torque motor I6 also. In the ordinary switch the joint operation of components 2I and 22 of torque motor I6 would then continue until housing I0 had moved back through "an angle equal to the differential angle of the switch, when the circuit through the switch would again be interrupted. In the present structure, however, completion of the circuit by the mercury not only energizes the second component of the torque motor, but also energizes electromagnetic member 33, drawing the the invention thus far described is to be found in the fact that at least one of the torque motors is at all times energized, even when the gyroscope is in the desired attitude. The arrangement is -also not efiicient in that whenever both the comffponents of any torque motor are energized at once, two-thirds of energy supplied is wasted in the opposition between these two components.

. The structure on the other hand has the advanmotion about both its precession axes, and therefore static friction is reduced to a minimum.

armature 32 down into contact with member 41,

and so tilting envelope in the same direction as that in which the torque is now effective.

Member 43 is adjusted so that the movement of armature 32 under the influence of electromag- There is shown in Figures 3, 4, 5 and 6 a modification of the invention in which torque motor tween opposed, simultaneously operating portions netic member 33 is almost but not quite equal to the differential angle of the switch so that as soon a the mercury has completed the circuit between the electrodes, the envelope assumes a,

change in the position of envelope 25 with re-- of the system. So far as members are common to Figures 1 and 3, they have been given the same reference numerals. Elements in Figures 4 and 5 related to similar elements in Figure 2 but not ,exactly the same will be given reference numerals 100 higher than those in Figure 1, and elements i having no counterparts in Figures 1 and 2 will be given other numbers in the series from 100 to 200. The same sort of assignment of numbers in the series from 200 to 300 will be made in Figure Figure 3 shows a casing II! in which a gyro- -scopic rotor is mounted for rotation by an electrical motor 23, in the direction indicated by spect to housing I0 almost equal to the differential angle of the switch but in the opposite direction again takes place. It will be apparent that by suitable adjustment of screws 36 and 43, it is possible toobtain almost any effective differen-- tial angle not greater than the actual angle of switch 24.

Five means for adjusting the system are provided. In the first place, the force exerted by:

-*-8 with respect to the Cardan ring I 2, which in turn is mounted for rotation about the axis 9 arrow II about a normally vertical axis 1. Casing I0 is mounted for rotation about the axis with respect to the support members I3 and I4.

- A torque motor I I5 is provided for applying torque so:

--a second torque motor H6 is provided for apbetween the housing and the Cardan ring, and

1 plying torque between the Cardan ring and the spring relative to that exerted by electromag-fl' net member 33 is adjustable by screw 56. In the second place, the rate of erection of the gyroscope due to component 22 only of torque motor I6 is adjustable by means of variable resistor 81. In the third place, a rate of erection of the gyroscope support member I4. Torque motor II5 comprises .two components III and I20, and torque motor IIB comprises two components I2! and I22. A

.first fluid switch I24 is mounted on the housing It] for responding to tilt of the housing about axis 8 and a. second fluid switch 224 is mounted the stabilized condition brought about by opera-' 1 tion of the mercury switch can be adjusted by screw} 36 so that the average position of housing. I0 is horizontal. In the fifth place, the effective differential angle of the switch may be adjusted.

by operation of screw 43.

' "opposite direction.

For the sake of completeness". a second fluid switch 24' 'is shown as mounted on Cardan ring I2 for response to movement of the gyroscope out of the horizontal position about the other horizontal axis. and its circuit connection are in every way analogous to those described in connection with Both the structure of this switch" mercury switch 24. Thuswinding 20 of torque motor I5 is continuously energized through conductors 94 and 86', variable resistor 81', conductor 30' and ground connection 9|. Winding I! of torque motor I5 is energized upon operation of- 2 switch 24' through conductor 94 and 82', variable resistor 83', conductors 84 and 65 and ground connection 61'. Winding SI of switch 24 is energized upon operation of the switch through conductors 93 and 63 and conductor 64' and ground connection 61'.

An identifying feature of the modification of Torque motors H5, III; are of identical construction. When component I2I of torque motor H6 is energized, for example, torque is applied between the Cardan ring I2 and support member I4 in a first direction, while when com- ;ponent I22 is energized, torque is applied between Cardan ring I? and support member I4 in the In this embodiment of the invention the arrangement is such that only one component of the torque motor is energized at any given time, and when the gyroscope is in its desired position neither component is energized. Before discussing the circuit by'whioh this is 1 accomplished, reference should be made to Figures 4 and 5, which show fluid switch I24 in detail.

Fluid switch I24 comprises a' support I3I and an armature I32 including an electromagnetic Support I3! housing ID by machine screws I 36: loosening a either one of these screws and-further tightening the other permits tilting of base member I34 about its curved portion in either direction with respect to housing I0. Support I3I also inatcludes :aeplatermember. l vI darwhich :is iastenedito amember ll s ilby'TmaChiIIEQSCI'BWS M5. iBlate member .I 46 ..includes 8,111 :1 upwardly iproj ecting 7. arm; t3 5' to: the toplof vwhichttheretis fixed; by any -snital'ile meams'la pivotrpin I ZQfrom'iwhiehiar-i.

: mature 7 L32. is .pendulous. JAdjustable.stopiscrews I43; including lock nuts" I M, are provided: jat

5 priseia' pair of solenoids IE5 I a :and 1' I5 I brinounted 1 :"on an insulating. tubular core I 52 of: magnetically non reactive' material between insulating :sspacers ""I 48. 'A core 1-4! of: magnetic. material; is arranged for sliding :movement within; tubular "member I 52 1 in: response tozmagnetic. flux. setup by electrical energization of ithe solenoids. -TrSet :screws I-'38:having lockinuts I39 are provided-to limitithes movement :of member 141 within-the coil.

Block. I 4 I is traversed by two of 'the'rrods I 49, "'to the centers of whichz'it is connected by pins 01: other :suitable "means. End plates {I60 and -ISI are provi'ded with apertures for-receiving tie rods I 59, tubularimeinber I52, and the ends :of

the envelope I of fluid switch I2 which--in-:

cludes a'globule of mercury I23 and electrodes 121,128," I29 andI3Il. Switch I24'isialso conlistruCtedso that'it'. has 'no dead spot, thatris,

the mercury I126" therein flows betweenthe-pairs =of electrodes I21, I28 and I29,

assembled'together tocomprise a unitary armature by'tightening the :nuts on thelends of tie rods I '49. The 1 whole assembly is, then mounted on pivot I42. Aispring'clip'member I is se- "cured to therear portion of member M2, and has a downwardly'extending forward portion which prevents block MI from sliding'oif'the pivot.

' Member 'I55'is of resilient material'and is provided with a depressed portion which engages 'the edges 'ofa curved recess in the upper surface of block MI so as'to give a slight centeringaction tending to maintain the armature in'its normally centered, circuit 'interrupting'position.

' The'fluid switch"hasthree output conductors 165,166, I61. Conductorl is connected through winding |5la and conductor I58 to electrode I21. Conductor I 56 is connected through windingIS Ib and 'conductor 'I59'to electrode I39. 'Conductor lfi'lis connected to electrodes I28 and I29.

"When fluid switch I24 is installed on housing III, the housing'isfirst' set level, and the switch is so adjusted by the setting of adjusting-screws I38 that when mercury globule I26 is at oneend "of the switch and sliding'core 'I 41 is at the opposite end of tubular member I52, armature I32 is in the same position, under the influence of =gravity, as it is when mercury globule I25 and sliding core I47 are at the other extremes of "their travel. The switch as a whole is adjusted by means of screws I36 so that the 'housingis "tilted'as'far from the horizontal in one direc- "tion when the mercury begins to move in a first "direction as it is tilted from the horizontal in the other direction when the mercury begins-to move in the opposite direction. From this it follows that if the diiierential angle of the switch were zero, the slightest departure of the housing "from thehorizontal in either directionwould re- I3ilwithout 1 -""stopping in an" intermediate position. .Ihe mercury switch and the electromagnetic member: are

housing I 0--will now be explained. J T Motor 23 :driving'the'rotor. 'of-Lthe: gyroscope isenergizedwhenever switchf'l3 is'closed. The erecting mechanism including? fluid switch "I24 and torque motor I I6 15- 'sult vin :completion mf a moi-responding electric -circuit.

:r'fstopr screws I dfls'arenowsa'djusted' soithati'move- =1nentbf .zarmature I132: awith r-respect to :support -member 'I:3I :is' limited :to;aritotal;angler-slightly =1ess than the idifierential ;angle of 1 the switch, I as was. done with the switch-shown; in-Figure:';2. i'The switchiisrnow incproper adjustment.

Z'Referring again ito Figure' 3, the 2circuitzjby which fluid-switch I24 :controls the attitudeiof is energized whenever switch 8 0c is closed.

Torque motor I IIi differs fromtorquer motor 16 in *that 'the torques exerted by the components IZI and I22 are exactly equal instead of havingaa 2to 1 ratio. "Adj-ustment of'the forces exerted by the two components of the torque motor is possible-by means of the setting of variable resistors" 83- and BI.

I Now suppose that housing 'I-ll is tiltedfrom" its -level attitude in such -a direction thatnits' lefthand portion a as I seen in Figure 4 moves downwardly to a considerableextent so that the mercury makes connection between electrodes JI-Z'I and I28; switch being-closed. Anelectrical circuit maybe tracedfromterminallllthrough conductors '15 and 'II, sw-itch 8B; conductorsBI,

85*and '86; variableresistor' fil;conductor flllycom- -=ponent-'-I22 oftorque motor H6, conductor -I65,

windin I 5 Ia;conductor-i58;- electrode 1 I 21; mer cury"l25, electrode I 28, ground conductors-"I67 and I4, switch '13, andconductor 12. Component I22 of-torque motor H6 is-accordingly energized to precess housing lfl so'thatthe left-hammertion'asseen in -Figure 4 is'-raised,and at the same time Winding I 5 Ia isenergized to slide core M? to the right as shown in Figure 4, so that its Weightshlfts the centerof "gravityof "the" armature; tiltingthe latter with respect to the housing through-an angle a-lmost'equal-to the-differential angle of the switch,so'that-only a slight-depar- .ture-oi thehousing from the horizontal in-the opposite direction is necessary to causeopposite energization of the torque motor.

7 It would be perfectly possible to use'a'duplicate or switch I24,for response to tilt' of'the gyroscope housing about the otheraXisQ-but there is 'illustrated in- Figure 6 a further modified form of-a mercury switch 224" equally' welladapted for use in' this application. -Iri-Figure= 6 the envelope 2z5 ofrthe mercuryswitch 224' is shown to "contain a globule ofmercury 226' and" electrodes *22 T3228,

22.? and 230 as before. Switch-2244ssimilarrto switch I 24 in that it also 'hasno dead; Spot. The

i switch also comprises an" armature '232Whibh' is 1vota1ly carried on a support member 23I in this modification "of the invention electromag- "netic' means'233 is" carried by the support member rather than by the armature.

-- Support member '-23I is-shown to comprise a downwardly c-urved base member "234 adjustably 65 mounted-on Cardan-ring' I2 in the same manner as was member I34 onhousing I0 inFigure' 4.

Machine screws 236 permit adjustingthe tilt of the 'supportmember with respect to the Cardan "ring, and'may be locked in adjusted position by "locknuts 236'; Support member 23! includes-a "plate member-24B which is fastened to member 234 -by*-ma'chine screws 245,and*w hich carries at its entremeend coils' 25M and 251 b comprismg portions of electromagneticmeans-2'33. Plate member-2404s of non-magnetic material; but the 9 cores 241a and 2411) of windings 25Ia and 25Ib are a ferromagnetic material. Plate member 240 has an upwardly extending arm 235 from which as before a pivot pin 242 projects. A block 24! is pivotally carried on pivot pin 242, and pivotally supports a strip 253 of ferromagnetic material which constitutes the principal element of armature 232, and which carries at its ends adjustable stop screws 243 complete with lock nuts 244, cooperating with plate member 240 to limit the movement of armature 232 with respect thereto.

Bracket means 260 and 26I are fastened to member 253 by machine screws 262, 263 and act as supports for envelope 225.

Electrical connection is made to the switch by means of conductors 265, 266 and 261. conductors, 255 is connected to one terminal of winding 25Ia, the other terminal of which is connected by conductor 258 to electrode 221 of the mercury switch. In a similar fashion conductor 266 is connected to one terminal of winding 25Ib, 1

the other terminal of which is connected by conductor 259 to electrode 230 of the mercury switch. Conductor 26'! is connected to electrodes 228 and 229 of the mercury switch,

Since in this modification of the invention there is no shifting weight, the adjustment of the switch is made by adjusting screws 236 so that the switch acts about a central position in which Cardan ring I2 is horizontal, in the same fashion that switch I24 was adjusted by means of screws I36. Stops 243 are then adjusted so that the amount of travel of the envelope with respect to the support member is slightly less than the differential angle of the switch.

Referring again to Figure 3, it will be seen that the operation of fluid switch 224 is in every respect the same as that of switch I24. By adjustment of variable resistors 83' and 81' the torques exerted by the components H1 and I of torque motor II5 are adjusted to be equal, and thereafter departure of the Cardan ring from a horizontal position is effective to energize the appropriate one of windings Ia and 25 lb at the same time that it energizes the appropriate component of the torque motor, so that although envelope 225 may comprise a mercury switch with a commereially feasible differential angle, the arrangement acts as though the mercury switch had a very small differential angle.

The embodiments shown in Figures 3-6 may further be modified to give a modulating type of gyroscopic erection by making a change in the relationship of parts while still utilizing the same structure disclosed in these figures. Referring specifically to Figures 4 and 6, the structure therein is modified only by the adjustment of the stops I43 and 243 such that the angular travel or displacement of the switch envelope with respect to the supporting member is greater than the differential angle of the respective switches. With thisnew arrangement of parts, the operation of the apparatus is substantially changed within a range of displacement of the gyroscope from a normal position which is equal to and less than the angular displacement or the switches I32 and 232. Within these ranges of gyroscope tilt, the switch mechanism I32, 232 will operate in a continuous oscillating manner, that is, the electromagnets of these switches will cause the switch envelopes to be tilted or oscillated between alternate contact making or circuit closure positions at a fixed rate independent of the position of the gyroscope upon which they are mounted. As the gyroscope is tilted or departs fromthe normal Of these completing the energizing circuits for the windings of the motor I20 and I2I in such a manner that one of the motor windings is energized for a longer period of time than the other winding and the over-all effect of the energization of the respective motors is an effective precession of the yroscope in a direction to overcome the tilt and erect the gyroscope. This type of energization is in proportion to the departure of the gyroscope from the normal position up to the point where the differential angle of operation of the armature and the electromagnet is exceeded by the tilt of the gyroscope. At this point and all angles beyond this point, the mercury of the respective switch envelopes will remain in contact with the electrodes which are positioned lowest from their normal position and operation of the electromagnet associated therewith will not rotate the switch envelope sufficiently to make the opposite contact. However, the influence of gravity will return the mercury to the former position. The associated erection motor will be energized in a direction to erect the gyroscope.

In a condition of still further tilt of the gyroscope from the normal position, the operation of the electromagnet to rotate the switch envelope will not be such as to cause disengagement of the mercury from the associated electrodes and the erection motor so energized will remain energized continuously until the gyroscope has precessed toward the neutral position up into the range where the oscillating type of switch operation and motor operation takes place.

In this latter embodiment of the invention, it will become apparent that the use of a mercury switch without a dead spot is not required. Further, the gyroscope erection motors because of the oscillatory type of operation of their controlling switches will be in a rate of substantially continuous energization. Since the rate of oscillation of the switches is greater than the rate of response of the erection motors, there will be only minute and insignificant oscillations impressed upon the gyroscope, and the erection system will erect, for all practical purposes, to a true vertical or reference position with variations therefrom which are imperceptible to the systems with which such gyroscopes are associated and to the human eye being exceedingly diflicult to measure. This switching apparatus provides a proper timing or modulating type of erection which is extremely sensitive and stable and permits rapid erection upon a wide departure of the gyroscope from the reference position. It also has a definite advantage over known erection systems in that it is continuously energized to maintain the reference position while the prior art methods require a departure of the gyroscope from the reference position before the erection apparatus begins to function.

The various switching apparatus and circuits described herein provide improved means of main.- taining the spin axis of a gyroscope vertical or substantially vertical and permit increased sensitivity in operation from relatively insensitive commercial switches. Further a modulating or proportioning action of a particular arrangement of the apparatus may be obtained from the associated erection system.

Numerous objects and advantages of the invention have been set forth in the description, together with details of the structure and function of the various modifications, and the novel feaaczacse tures thereof have been clearly disclosed; Thedisclosure, however,- is illustrative only and changesmay be madein detail, especially in matters of shape, size and arrangement of parts, within the principle of the invention, to the full extentindicated by the broad general meaning of the terms inwhich the appended claims-are expressed.

I claim as my. invention 1. Means for responding to tiltingof a tiltable body comprising, .in combination a fluid switch tiltable through a selected'diflerentialangle between opposite circuit controlling conditions;.

means for tiltably supporting said switch upon suchabody, so as to be'subject td-any'tilting.

movement thereof; electrically energized means for! causing limited tilting movement of said switch with respect tosaid Supporting means independent-of tiltingof; said means, through an angle not: greater than said :selected' differential angle; and means connecting said switch to said. last named means soith'at the staterofuenergization thereof is changed uponchange in thelcircuit controlling. condition of said switch;

2. A device of the 'class des-cribedcomprising, incombination, a supportmemberfor mounting upon atiltable body; an arma'tureflpivo-tallycarri'edron said support J member, a fluid switch carried by said armature and. having a selected difirential 'angle, electrically energized means' carriedby said support :member for cooperating with said; armature. to cause: pivotal movement thereof :withi respect to said member, means limiting saidvpivotal movement to. an angle less than said differential angle, andsmeans connecting saidxfluid switch to said first named mea-ns forucontrolling the operation :thereof.

3. A device of; the 'classidescribed comprising. in .'com"bina'tion, a supportlmember form'ountingh uponia tiltabl-e 'body, an armature pivotally carriedson said: su'pport'member a fluid switch carried =-by isai-d armatureand :having a selected dif ferentialtangle,-.means includin a pair: of coilsv for .electromagneticallycausingv pivotal movementscf: said armature, mean-s limiting 'said .piv-

otallmovement to an angle.- lesg-than said differ entialzangle; and meansconnectinglsaid fluid.

switch l to, said first nam'ed means .for controlling theoperationthereof;

4;:;A:.device oftheclassxdescribed comprising, r

in combination, ;a support member for mounting, upon a tiltablebody, an armature p-ivotallyicar', ri-ed bysaid :support member, a fluidzswitch .car-. ried-rbysaid armature and having a selected .dif-

ferential. angle, meansvincluding. az-pair of coils carriedby-said armature for electromagnetically causing; pivotal :movement .ofrsaid armature with respect: to said supportmember, means limiting said pivotal movement to an angle less than said differential angle, and: means connecting. said fluid .switch to said .first named meansforcontrolling the operation thereof.

5-. A: device of Y the. class described comprising,

incombination, a support member for mounting", upon aitil-ta'ble body, an armature'pivotally carriedonsaid supp-ort member, a fluid switch carriedtbysaid armature andhaving a selected-diff ferentialangle, electromagnetic means including a pair of coils-carriedby said support member forcooperating with said armature to cause: pivotal movement thereof, and means limiting saidpivotal movement to an angle: less than said differential angle, and means connecting said fluid switch to. said electromagnetic means for controllingthe operation thereof.

6. A device of the-class described comprisingin combination, a support member for mounting upon a tiltable body, an armature, a fluid switch carried by said armature and having a selected differential angle, means pivotally. mounting said armature upon said support member and urging said armature into a first position, and electri-- cally energized means. carried by said support member for cooperating with said armature to cause pivotal movement thereof from saidfirst position, and means connecting said fluid switch to said electrically energized means-for control ling the operation thereof.

7. A device of the class described comprising,-;

in combination-a support member for mounting upon a tiltable body,'an annature, a fluid switch. carried'by said armature and having aselected. diiierential angle, means pivotally mounting said. armature upon said support memberand urging. said armature into a first position, electrically, energized means carried by said support member for cooperating with said armature to cause pivotal movement thereof from said first'position and means including said fluid switch for ener-' gizing said electrically energized means only when said armature is in said first position.

8. In combination: a member which istobe maintained in a predetermined position; a fluid switch tilta'ble through aselected differential angle between opposite circuit controlling positions; means tiltably supporting said switch upon said member so as to be subject to tilting movement thereof away from said predetermined position; means con-trolled. upon tilt of said switch into either of said circuit controlling positions to produce an effect upon said member tending ;to tilt said-switch out-of said position; and means, energized upon .tilt of said switch into either of said circuit controlling positions, for causing independent tilting of said switch with respectto: said member through an angle notgreater than.

said. selected differential angle.

9. In combination: a member which is tobe maintained in a predetermined position; a fluid: switch tiltable through a selected differential. an glebetween opposite circuit controlling positions; means tiltably suppor-tingsaid switch uponsaid. member so as to be subject to tiltingmovement. thereof away from said predetermined positiom .means controlled upontilt of. said switch into either of said circuit controllingpositionstoproduce-an effect upon saidmem-ber. tending to tilt. said. switch-out: of said position; and means, ens.- ergizedupon tilt of said switchint-o eithersof-saidcircuit controlling: positions, for. causingmindependent tilting of said switch withrespec-t :tosaid. v, memben'through an. angle "not greateralthansaid selected: (inferential:v angle,.. and in a-directiontending; to; move saidswi-t-ch out of said circuit controlling positions;

opposite direction.

11. A device ofthe class described comprising, in combination: a gyroscope; means mounting said gyroscope for oscillation about a normally horizontal axis; a fluid switch; means mounting said switch for limited movement, from a normal position, about a, pivotal axis; means supporting said mounting means for oscillation with said gyroscope so that said axes are substantially parallel; erecting means for said gyroscope; electrically actuable means for causing said limited movement of said switch; and means connecting said switch in controlling relation to said erection means and said last named means, so that upon departure of said gyroscope from a, normal horizontal position said switch is tilted in a direction to control said erection means and said electrically actuated means for returning said gyroscope to said horizontal position and causing movement of said switch about said pivotal axis in the same direction as that in which said erection means is acting.

12. A device of the class described comprising, in combination, a support member for mounting upon tiltable body, an armature pivotally carried on said support member in pendulous relation thereto, a fiuid switch carried by said armature and having a selected difierential angle, a weight movable along said armature to alter the position of the center of gravity thereof so as to gravitationally cause said pivotal movement, electromagnetic means comprised in said armature for moving said weight, means limiting said pivotal movement to an angle less than said differential angle, and means connecting said fluid switch to said electromagnetic means, for controlling the operation thereof.

13. A device of the class described comprising, in combination: a fluid switch tiltable between a first position, in which it establishes a first circuit condition, and a second position, in which it establishes a second circuit condition, said positions being spaced by tilting of said switch through a minimum differential angle; means mounting said switch for tilting movement through an angle less than said difierential angle; a member tiltable through an angle greater than said differential angle; means supporting said mounting means upon said member for tilting movement unitary therewith; means causing tilting of said switch in either of two opposite directions in said mounting means; and means connecting said switch in controlling relation to said last named means, so that tilt of said switch due to movement of said member in a first direction energizes said tilting means to cause said limited movement of said switch in the opposite direction.

14. Means for responding to tilting of a tiltable body comprising, in combination: a fluid switch tiltable through a selected differential angle between opposite circuit controlling conditions; mean for tiltably supporting said switch upon such a body, so as to be subject to any tilting movement thereof; electrically energized means for causing limited tilting movement of said switch with respect to said supporting means independent of tilting of said means, through an angle greater than said selected differential angle; and means connecting said switch to said last named means so that the state of energization thereof is changed upon change in the circuit controlling condition of said switch.

15. In combination: a member which is to be maintained in a predetermined position; a fluid switch tiltable through a selected differential angle between opposite circuit controlling posi- 1'4 tions; means tiltably supporting said switch upon said member so as to be subject to tilting movement thereof away from said predetermined position; means controlled upon tilt of said switch into either of said circuit controlling positions to produce an efiect upon said member tending to tilt said member toward said predetermined position; and means, energized upon tilt of said switch into either of said circuit controlling positions, for causing independent continuous oscillatory tilting of said switch with respect to said member through an angle greater than said selected difierential angle.

16. In combination: a member which is to be maintained in a predetermined position; a, fluid switch tiltable through a selected differential angle between opposite circuit controlling positions; means tiltably supporting said switch upon said member so as to be subject to tilting movement thereof away from said predetermined position; means controlled upon tilt of said switch into either of said circuit controlling positions to produce an efiect upon said member tending to tilt said switch out of said position; and means, energized upon tilt of said switch into either of said circuit controlling positions, causing continuous oscillatory tilting of said switch With respect to said member through an angle greater than said selected difierential angle and independently of the tilting of said member within limits of tilt of said member which is not greater than said selected differential angle of said switch.

17. Means for responding to tilting of a tiltable body comprising, in comination: a fluid switch which is tiltable through a selected differential angle between the opposite circuit controlling conditions; means for tiltably supporting said switch upon said body such as to be subject to any tilting movement thereof; electrically energized means for causing continuous oscillating movement of said switch with respect to said supporting means independent of the tilting of said body; and means connecting said switch to said last named means such that the state of energization thereof is changed upon change in the circuit controlling condition of said switch.

18. A device of the class described, comprising, in combination: a gyroscope; means mounting said gyroscope for tilt about a pair of mutually perpendicular axes; a fluid switch; means mounting said switch for limited movement from a normal position about a pivotal axis; means supporting said mounting means for tilt with said gyroscope such that one of said perpendicular axes and said pivotal axis are substantially parallel; a reversible erecting means for said gyroscope; electrically energized means for caus ing continuous oscillating movement of said mounting means and said switch through said limited movement independently of the tilting of said body; and means connecting said switch in controlling relation to said erection means and said electrically energized means, so that upon departure of said gyroscope from a normal position said switch is tilted as it is oscillated to energize said erection means more in one direction than in the other to return aid gyroscope to said normal position.

19. A device of the class described comprising, in combination: a support member for mounting upon a tiltable body, an armature, a fluid switch carried by said armature and having a selected differential angle, means pivotally mounting said armature upon said support and urging said 

